Analytical Study of the Confining Medium Diameter Impact on Load-Carrying Capacity of Rock Bolts

The force transfer of fully grouted rock bolts is playing a significant effect in determining the rock reinforcement quality. To evaluate the performance of rock bolts, laboratory pulling tests were commonly used. Experimental tests proved that the confining medium diameter had an effect on the rock bolting performance. However, little analytical work has been performed to investigate the impact of the confining medium diameter on rock bolt load-carrying capacity. Therefore, this paper analytically studied the confining medium diameter effect on the load-carrying capacity of rock bolts. It was found that the load-carrying capacity of rock bolts was obviously affected by the confining medium diameter. Moreover, the larger the confining medium diameter, the higher the load-carrying capacity of rock bolts. However, the ascending rate of the load-carrying capacity gradually declined. This load-carrying capacity variation trend consistently agreed with experimental results. Moreover, with the confining medium diameter ascending, the load-carrying capacity variation trend was consistent when the confining medium modulus was under different levels. Last, it was found that, with the confining medium modulus ascending, the critical influence diameter gradually dropped.